1. Field of the Invention
The present invention relates to an ultrasound diagnostic apparatus that generates an ultrasound tomographic image by using ultrasound.
2. Description of the Related Art
Conventionally, ultrasound probes that use piezoelectric elements have been known, but in recent years, ultrasound probes that use broadband capacitive ultrasound transducers (called the C-MUTs) have been developed.
For example, as disclosed in Japanese Patent Application Laid-Open Publication No. 2008-516683 as a first conventional example, an ultrasound diagnostic apparatus that can be used by being connected with such ultrasound probes has been proposed. The C-MUT has a cavity on a silicon substrate and electrodes are provided over and under the cavity.
Bias voltages as well as ultrasound drive signals are applied onto these electrodes to vibrate a film at the top of the cavity, thereby transmitting ultrasound, and an echo signal that comes back is detected by the film at the top, so that the transmission and the reception of the ultrasound are achieved.
The C-MUT can be achieved using a MEMS (Micro Electro Mechanical Systems) process as well as the C-MUT can be smaller than a piezoelectric transducer because the size of one element is smaller. A technique has also been proposed in which the C-MUT, which can be smaller than a piezoelectric transducer, is connected with a drive shaft and used with an extra-fine ultrasound probe.
In addition, there are ultrasound diagnostic apparatuses that are implemented by arranging a plurality of ultrasound transducers and obtain ultrasound tomographic images by selecting some of the ultrasound transducers to perform transmission and reception. As a second conventional example, International Publication No. 2001/021072 discloses a structure in which a multiplexer is implemented at a probe distal end part close to ultrasound transducers.